The COVID-19 virus, caused by SARS-CoV-2, frequently affects the cardiovascular system, often manifesting as changes to the heart rate. These alterations can occur during the initial phase of illness and may persist for months after the infection has cleared. Understanding how the virus influences the heart’s rhythm is important for recovery, as effects can range from temporary fluctuations during the acute phase to more lasting conditions requiring medical attention.
Heart Rate Changes During Active COVID Infection
During the acute phase of COVID-19, many people experience tachycardia, an elevated heart rate. This acceleration is often a predictable response to the body fighting a severe infection, driven by fever, systemic inflammation, and dehydration. The heart speeds up to circulate blood and immune cells more rapidly, a natural response compounded by the stress of illness.
A less common phenomenon is relative bradycardia, where the heart rate is inappropriately low despite a high fever. Normally, the heart rate increases by about 10 beats per minute for every degree Celsius rise in body temperature. The failure to meet this expected increase suggests unusual interference with the body’s normal regulatory signals.
In some hospitalized cases, true bradycardia (a heart rate below 60 beats per minute) has been observed. This slowing may be associated with severe inflammation or direct effects on the heart’s electrical system. These changes during active infection highlight the virus’s ability to destabilize the heart’s rhythm even in the short term.
Persistent Heart Rate Abnormalities After Recovery
Heart rate issues often continue for weeks or months after the initial infection, falling under Long COVID symptoms. Persistent rapid heart rates are common, frequently presenting as Postural Orthostatic Tachycardia Syndrome (POTS) or inappropriate sinus tachycardia (IST). Both are forms of cardiovascular dysautonomia, a malfunction of the nervous system that regulates involuntary body functions.
Postural Orthostatic Tachycardia Syndrome involves an excessive heart rate increase when moving from lying down to an upright position. POTS is diagnosed by a sustained increase of at least 30 beats per minute within 10 minutes of standing, without a drop in blood pressure. This spike is the body’s attempt to compensate for dysfunctional blood vessel constriction, causing lightheadedness, brain fog, and fatigue (orthostatic intolerance).
Inappropriate sinus tachycardia is characterized by a consistently elevated resting heart rate, typically over 100 beats per minute, even without physical activity or other stressors. Unlike POTS, IST is not triggered by posture change but represents a persistently high baseline rate. This is thought to result from the heart’s natural pacemaker, the sinus node, firing too quickly due to neurological or inflammatory changes.
How COVID Disrupts Cardiac Rhythm Regulation
The heart rate irregularities are caused by two primary pathways: direct tissue injury and autonomic nervous system (ANS) disruption.
Direct Tissue Injury
The SARS-CoV-2 virus can trigger widespread inflammation, sometimes leading to a “cytokine storm.” This systemic inflammation can cause myocarditis, which is inflammation of the heart muscle itself. When the heart muscle is inflamed, its electrical pathways are disrupted, leading to abnormal rhythms. Even without direct viral infection, inflammatory markers can damage and scar heart tissue, altering the precise electrical signals needed for a steady heartbeat.
Autonomic Nervous System Disruption
The second, more enduring mechanism is ANS disruption. The ANS is the body’s involuntary control system, governing heart rate, breathing, and digestion. COVID-19 can cause dysautonomia by attacking parts of the nervous system, such as the vagus nerve, or by triggering autoantibodies. These autoantibodies mistakenly attack nerve cell receptors that control the balance between the sympathetic (“fight or flight”) and parasympathetic (“rest and digest”) branches. An imbalance results in the persistent or positional tachycardia seen in POTS and IST.
When to Monitor and Seek Medical Attention
Monitoring heart rate, often using wearables or manual pulse checks, is practical during recovery. While temporary fluctuations are expected, certain signs require medical evaluation. A resting heart rate persistently above 100 beats per minute, or a heart rate that feels irregular or frequently pounds, should prompt a conversation with a healthcare provider.
To check for POTS, lie down for five minutes and record your heart rate. Then stand up and record your heart rate again at the two, five, and ten-minute marks. A sustained increase of 30 beats per minute or more warrants further medical investigation.
Immediate medical attention is required for more concerning warning signs. These include new or worsening chest pain or discomfort, significant shortness of breath disproportionate to activity level, or experiencing dizziness, lightheadedness, or fainting (syncope). Seeking medical evaluation is advised if any heart-related symptoms continue or worsen four weeks or more after the initial infection.